JJG 1033-2007 English PDF (JJG1033-2007)

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JJG 1033-2007: Verification Regulation of Electromagnetic Flowmeters
JJG 1033-2007
JJG
METROLOGICAL VERIFICATION REGULATION
OF THE PEOPLE’S REPUBLIC OF CHINA
Electromagnetic flowmeters
ISSUED ON: NOVEMBER 21, 2007
IMPLEMENTED ON: FEBRUARY 21, 2008
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC.
Table of Contents
1 Scope ... 5
2 Normative references ... 5
3 Terms ... 5
4 Overview ... 6
4.1 Working principle ... 6
4.2 Structure and use ... 6
5 Measurement performance requirements ... 7
5.1 Accuracy grade ... 7
5.2 Fiducial error ... 7
5.3 Error expression method and selection principle ... 7
5.4 Repeatability ... 7
6 General technical requirements ... 8
6.1 Accompanying documents ... 8
6.2 Marking... 8
6.3 Appearance ... 9
6.4 Tightness ... 9
6.5 Protection function ... 9
7 Measuring instrument control ... 9
7.1 Verification conditions ... 9
7.2 Verification items and verification methods ... 12
7.3 Handling of verification results ... 18
7.4 Verification cycle ... 19
Appendix A Type evaluation outline ... 20
Appendix B Format of verification certificate and verification result notice (inner page)
... 31
Verification regulation of electromagnetic flowmeters
1 Scope
This Regulation applies to the type evaluation, initial verification, subsequent
verification, in-use inspection of electromagnetic flowmeters (hereinafter referred to as
flowmeters), which are installed in closed pipelines. It is not applicable to flowmeters
for measuring blood, liquid metal, iron ore slurry and open channel flow measurement,
nor is it applicable to the verification of insertion electromagnetic flowmeters and
electromagnetic water meters.
2 Normative references
The provisions contained in the following standards and regulations constitute the
provisions of this Regulation through reference.
JJF 1004-2004 Metrological terms and their definitions for flow rate
GB/T 18659-2002 (idt ISO 9104:1991) Measurement of fluid flow in closed
conduits - Methods of evaluating the performance of electromagnetic flow - Meters
for liquids
GB/T 18660-2002 (idt ISO 6817:1992) Measurement of conductive liquid flow in
closed conduits - Method using electromagnetic flowmeters
JB/T 9248-1999 Electromagnetic flowmeters
It shall be noted that the current valid versions of the above references shall be used.
3 Terms
3.1 Primary device (sensor)
A device used to generate a signal proportional to the flow rate. The primary device
mainly includes the following units:
- A measuring tube through which the conductive liquid to be measured flows; its
inner surface is usually electrically insulated;
- One or more pairs of radially opposed electrodes, which are used to measure the
signal generated by the flow of the conductive liquid;
- An electromagnet that generates a magnetic field in the measuring tube.
3.2 Secondary device (converter)
A circuit device, that converts the induced electromotive force taken from the
primary device into a standard output signal proportional to the flow rate.
3.3 Meter characteristic coefficient
A parameter that can change the metering performance of the flowmeter by
modifying its value.
Note: 1. Due to different processes or names of flowmeters produced by different
manufacturers, this parameter may be a sensor coefficient, a converter coefficient, a
correction coefficient or other parameter;
2. This parameter may consist of one or a group of parameters.
3.4 Flow conditioner
A component that can reduce vortices and improve velocity distribution.
3.5 Fiducial error
The error of the flowmeter divided by the specific value of the flowmeter.
Note: This specific value is generally called the reference value, which can be the upper
limit of the flowmeter's range or nominal range.
4 Overview
4.1 Working principle
In a closed pipe, a magnetic field perpendicular to the flow direction is set up. The flow
rate is calculated by measuring the induced electromotive force generated by the
movement of the conductive liquid in the magnetic field.
4.2 Structure and use
The flow meter consists of a primary device and a secondary device. According to the
combination of the primary device and the secondary device, the flow meter can be
divided into a split type and an integrated type. The flow meter is mainly used to
measure the volume flow of conductive liquids.
7.1.1.2 The expanded uncertainty of the device measurement result shall not be greater
than 1/3 of the absolute value of the maximum allowable error of the flow being tested.
7.1.1.3 When the vapor pressure of the verification liquid is higher than the atmospheric
pressure, the device shall be closed.
7.1.1.4 The electrical equipment used for verification shall be grounded.
7.1.1.5 The equipment used to collect the output signal of the meter being tested during
the verification shall match the collected signal and meet the verification requirements.
7.1.1.6 If the instantaneous flow of the meter being tested is calibrated, the flow stability
of the device shall meet the following requirements: For flow meters with an absolute
value of the maximum allowable error equal to or less than 0.5%, the flow stability of
the device shall be better than 0.2%; for flow meters with an absolute value of the
maximum allowable error greater than 0.5%, the flow stability of the device shall be
better than 0.5%.
7.1.2 Verification liquid
7.1.2.1 The verification liquid can generally be clean water without air, fibers, magnetic
particles and other visible particles. If other liquids are used, their type (including
commercial name), viscosity, density, conductivity shall be stated in the verification
certificate.
7.1.2.2 During the verification, the liquid shall always fill the test pipe and flow in a
single phase, stable and vortex-free manner.
7.1.2.3 The pressure of the verification liquid at any point in the pipeline system and
flowmeter shall be higher than its saturated vapor pressure. For easily vaporized
verification liquids, there shall be a certain back pressure downstream of the flowmeter.
The recommended back pressure is 1.25 times the saturated vapor pressure of the
verification liquid at the highest verification temperature.
7.1.2.4 The conductivity of the verification liquid shall be in the range of 5 mS/m (50
µS/cm) to 500 mS/m (5000 µS/cm), or determined separately according to the technical
indicators given by the flowmeter manufacturer.
7.1.2.5 The temperature range of the verification liquid shall be between 4 °C and 35 °C.
During each verification process at each flow point, the liquid temperature change shall
not exceed ±0.5 °C.
7.1.3 Verification environmental conditions
7.1.3.1 Atmospheric environmental conditions shall generally meet the following
requirements:
- Ambient temperature: 5 °C ~ 35 °C;
- Relative humidity: 15% ~ 85%;
- Atmospheric pressure: 86 kPa ~ 106 kPa.
7.1.3.2 The AC power supply voltage shall be (220 ± 22) V; the power supply frequency
shall be (50 ± 2.5) Hz. A suitable AC or DC power supply (such as a 24V DC power
supply) can also be used, according to the requirements of the flow meter.
7.1.3.3 The external magnetic field shall be small enough to have negligible effect on
the flow meter.
7.1.3.4 Mechanical vibration and noise shall be small enough to have negligible effect
on the flow meter.
7.1.4 Installation conditions
7.1.4.1 Length of straight pipe segment on the upstream a...